﻿<p>The <em>IfcBSplineSurfaceWithKnots</em> is a general form of rational or polynomial parametric surface in which the
knot values are explicitly given.</p>
<blockquote class="extDef">
NOTE&nbsp; Definition according to ISO/CD 10303-42:1992<br>
This is a B-spline surface in which the knot values are explicitly given. This subtype shall be used to represent
non-uniform B-spline surfaces, and may also be used for other knot types.<br>
All knot multiplicities except the first and the last shall be in the range
1,....,<i>d</i>; the first and last may have a maximum value of <i>d</i> + 1. In evaluating the basis functions, a knot
<i>u</i> of, e.g., multiplicity 3 is interpreted as a sequence <i>u</i>, <i>u</i>, <i>u</i>, in the knot array.
</blockquote>
<blockquote class="note">NOTE&nbsp; Entity adapted from <strong>b_spline_surface_with_knots</strong> defined in
ISO10303-42.</blockquote>
<blockquote class="history">HISTORY&nbsp; New entity in IFC4.</blockquote>